A babysitter who battered a two-year-old girl to death on his 15th birthday was today ordered to be detained for at least 15 years.

Karl McCluney kicked, punched and bit Demi Leigh Mahon, leaving her with 68 injuries including brain damage. She died two days later. McCluney, now 16, was convicted of murder last month.

Yesterday at Liverpool crown court, Mr Justice Sweeney described the murder as "savage". The judge said: "You were extremely fed-up with having to babysit because it was your birthday, nobody had planned anything for you and you did not think that was fair.

"At the flat, Demi Leigh was crying and you became angry with her.

"You were large and powerful, she was only a small child and stood no chance against your onslaught."

Demi Leigh was left with McCluney by her mother, Ann Marie McDonald, on 15 July last year while she went to cash her child benefit. The teenager took Demi Leigh to the park before carrying out the attack at his home in Eccles, Salford.

He has never explained his actions, apart from alluding to the fact that Demi Leigh's behaviour was annoying him. McCluney's lawyer, Stephen Meadowcroft, said he had been diagnosed with a "significant conduct disorder" and a development age of between six and nine.

"The truth is, he has limitations that make him a young man of far less than 15 years old," Meadowcroft said.

The judge told McCluney: "You will not be released until such time as it is decided you no longer pose a danger.